Three-Phase Current Sensor Correction for Torque Ripple Reduction
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Solution Overview
Problem
Current sensors in vehicles, particularly those used in three-phase electrical systems, suffer from offset and gain errors due to temperature variation and aging, leading to torque ripple and torque offset issues.
Innovation Solution
A system and method for evaluating current sensor measurements by applying a transformation to generate reference currents, correlating current angles to a second-order harmonic function to determine gain errors, and using low pass filters to correct offset errors, with dynamic gain correction to minimize torque ripple and torque errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If current sensors are used in three-phase electrical systems, then motor control is enabled, but offset and gain errors occur due to temperature variation and aging
Solution Approach 1:
The system performs preliminary error characterization by correlating current angles with second-order harmonic functions to determine gain errors, and applies low-pass filtering to identify offset errors before they affect motor control. This proactive error detection and correction approach prevents measurement inaccuracies from degrading control performance.
Solution Approach 2:
The system continuously monitors current measurements, correlates them with rotational position, and uses the resulting error patterns to dynamically adjust gain and offset corrections. This closed-loop feedback mechanism compensates for temperature variation and aging effects, maintaining measurement precision over time and across operating conditions.
2Measurement precision
If gain correction is applied to correct measurements, then measurement accuracy improves, but torque ripple and torque offset errors may be introduced
Solution Approach 1:
The system applies different correction strategies to different phases based on their individual error characteristics. By correlating current angles with second-order harmonic functions, it identifies phase-specific gain errors and applies targeted corrections. This localized approach ensures accurate compensation without introducing uniform torque ripple across all phases.
Solution Approach 2:
The system dynamically adjusts correction parameters based on operating conditions. By monitoring the correlation between current angles and harmonic functions, it adapts gain and offset values in real-time, optimizing the balance between measurement accuracy and torque smoothness across varying load and temperature conditions.
3Measurement precision
If complex error correction algorithms are implemented, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The system introduces intermediate processing steps that simplify complex error correction. By using low-pass filtering to separate offset errors from dynamic components, and using harmonic correlation to extract gain errors, it breaks down the complex correction task into manageable stages. This intermediary approach maintains high measurement accuracy while keeping the computational burden acceptable for real-time implementation.
Data Source
AI summary
A system for evaluating current sensor measurements includes a current sensor configured to measure three-phase alternating current (AC) signals applied to a three-phase electrical device, the measured AC signals including a first measurement of a first phase current, a second measurement of a second phase current and a third measurement of a third phase current, and an error detection module configured to receive the measured AC signals. The error detection module is configured to apply a transform to the measured AC signals to generate a plurality of reference currents, each reference current of the plurality of reference currents represented as a current vector rotating in a two-dimensional reference frame, calculate a current angle between the plurality of reference currents, correlate the current angle to a second order harmonic function, and determine a gain error associated with the measured AC signals based on the correlating.